Centrific
â
Centrifuge
Model 228
Cat. No. 04-978-228 (115V)
04-978-229
(230V)
The Model 228 Centrific Centrifuge is
a portable, bench-top centrifuge
designed for clinical, educational. and
industrial applications. The Centrific
Centrifuge features a 6-place 45
°
angle nylon rotor and nylon shields
which will accommodate tubes ranging
in size from 7 to 17mm in diameter
and 100 to 133mm in length. This
includes 7ml, 10ml, and 15ml
Vacutainer* tubes. Additionally, Tube
Adapters 4-978-23 are available to
accommodate the smaller 10-13 mm
diameter by 75 mm long tubes.
The unit operates at a fixed speed of
3300 rpm and develops an RCF force
of 1380 x G. Sedimentation is
controlled by centrifugation time. The
motor is thermally protected and has
permanently lubricated ball bearings.
The cast iron base and vibration
isolation mounting provide additional
stability.
The feet on which the centrifuge rests
incorporate suction cups which adhere
to smooth benchtops. This serves to
reduce the movement of the unit due
to vibration. In order to prevent
damage to these feet,
never pick the
unit straight up off of the benchtop.
Always slide the unit off of the edge
of the work surface.
The Centrific Centrifuge also features
a 15 minute timer with a hold position
to give the user the option of
continuous operation. The time
selector functions as the power switch,
engaging the motor when the run time
has been set and the lid is closed.
The Model 228 has a lid latch to
positively secure the lid closed. The
latch is operated by a knob located at
the front of the lid. The latch operates
through a quarter turn.
Warning: Always be sure that the lid is
latched before operating the unit
.
*Vacutainer is a registered trademark of
Becton-Dickinson Co.
UNPACKING
Each Fisher Centrific Centrifuge is
shipped in a single carton. Carefully
unpack the carton and check the
contents against the packing list
below. Should a discrepancy exist,
notify your Fisher branch or
representative.
NOTE: If damage is observed, keep
the shipment intact -- including the
carton and all packing material -- and
file
a
claim with the final carrier.
Usually the firm will send an
investigator to ascertain liability.
Qty Item
Part No.
1 Centrifuge Assembly
04-978-228 (115v) 50775
or 04-978-229 (230v) 50867
1 Rotor, Cat.No. 04-978-232 50779
6 Shield, Cat.No. 04-978-233 50780
1
Thumbscrew
04-978-228 (115v) 38816
or 04-978-229 (230v) 50864
1 Instruction Manual
70906
INSTALLATION
To install the Model 228 Centrific
Centrifuge, perform the following:
1. Place centrifuge base on a flat
level surface.
2. Remove the six shields from their
packing and carefully insert them
into the six holes in the rotor.
3. Place rotor on drive shaft. Align flat
on drive shaft with hole position "1"
on rotor.
4. Secure rotor (with supplied thumb-
screw) onto drive shaft.
CAUTION:
Apply finger-tight
pressure only: do not use
wrench or other tool.
5. Be sure that the six shields are in
place. Never run the unit without all
shields in place
.
CONTROLS
Lid-Power Interlock
The lid interlock is designed to
interrupt power to the motor whenever
the lid is opened. This interlock is
implemented by a leaf switch. The lid
should not be used as an ON/OFF
switch.
Time Control
The time control is the power switch
for the motor. To start a run, the time
control is simply turned to the desired
centrifugation time. During the run, the
timer rotates counterclockwise to
indicate the time remaining. The user
may also use the “hold” feature to
make self-timed runs by placing the
time control into its HOLD position.
OPERATION
Centrifuge operation involves simply
loading the rotor, closing and latching
the lid, and selecting a centrifugation
time. The rotor must be properly
loaded to achieve good sedimentation
and vibration-free operation. Tubes of
the same capacity and load must be
placed 180 apart. Use water, if
necessary, to balance the load if there
is an odd number of tubes. Balance
load to within 1.0 gram.
NOTE: Never use shot, weights, or
mercury in tubes or shields.
Procedure
To operate the centrifuge, perform the
following:
1. Turn the time control to OFF.
2. Connect the unit to an appropriate
power source.
3. Unlatch and open lid; place tubes
into rotor in a balanced pattern.
4. Close and latch the lid.
5. Rotate the time control CW
beyond, then CCW back to,
desired setting.
6. When the rotor has stopped
spinning, raise the lid and remove
the tubes.
Determining Relative
Centrifuge Force
To determine the relative centrifugal
force (RCF), RPM and tube tip radius
must be known. Different rotor loads,
tubes, line voltage, and condition of
the centrifuge will affect the RPM. An
access hole for a phototachometer is
provided in the lid. The tube tip radius
is defined as the distance from the
center of the shaft to the farthest end
of the tube. When installed in the
rotor on the Model 228, this distance
is fixed at 11.32cm with shields
installed, but with no tube adapters or
cushions.
RCF is defined as the force acting on
a sample being centrifuged relative to
the force, due to gravity, that normally
acts on it. Such force must take into
account the tip radius of the installed
tube and the RPM at which it's
spinning. Assuming that the normal
gravitational force is at sea level, the
following formula expresses the
strength of the gravity field to which a
sample is subjected.
INSTRUCTIONS
